Structures for reflecting electromagnetic radiation have been constructed utilizing a membranous element on an underlying structure that imparts a desired contour to the membranous element. Previous activity in this area has been concerned with shaping tensioned double curvature membranes. This cannot be achieved passively with known materials. Therefore, some sort of loading, pressure, or actuation on the interior region of the membrane surface is required to impart the desired shape to the membrane.
From the standpoint of thermodynamics and structural deformation such loading is undesirable since it introduces irregularities or obscurations on the optical surface at the interior of the membrane area, exactly where the optic is most sensitive. Therefore, complicated mechanical and thermal control systems must be designed as well as new materials and adhesives must be developed. The time frame for such development in the current Art has been postulated to be approximately 10-20 years. Also, very involved actuation control systems and new material developments are envisioned for known systems, which impose undesirable complexity and uncertainty to the overall optical design.